1. Field of Invention
This invention relates to a moisture-indicating device for a wet pick-up vacuum cleaner. More particularly, this invention relates to a device for detecting when a wet extraction type carpet cleaner is extracting liquid from a carpet and indicating such a condition.
2. Description of Prior Art
Upon reviewing consumers operating wet extraction type suction cleaners in their homes, it has been observed that the consumer will often inadequately extract cleaning liquid from some areas of the carpet or even the entire carpet. Some consumers forget to extract any of the cleaning liquid from some areas of the carpet. Failure to adequately extract the cleaning liquid leaves the carpeting wet or overly damp. The carpeting, underlying padding and even the underlying flooring may consequently be damaged by water remaining in the carpet. Leaving the carpet overly damp may also lead to mold and mildew formation in the carpeting, possibly causing damage to the carpeting and creating a possible health hazard. Furthermore, failure to fully extract the soiled cleaning liquid from the carpet leaves dirt in the carpet that would other-wise be extracted from the carpet.
There is a need in the art of wet pickup vacuum cleaners and wet extraction type carpet cleaners for a moisture sensor and indicator device that can sense when the cleaner is picking up liquid and indicate such a condition to the operator via an audible or visible signal. Such a device would prompt the operator to continue to pick up liquid from a wet area of carpeting until the cleaner is no longer picking up any liquid. Thus, an operator would be less likely to insufficiently extract liquid from the carpet. The operator can be assured that the soiled cleaning liquid is removed from the carpet to the fullest extent possible and that the carpet is left only slightly damp and will quickly air dry. Moreover, water damage to the carpet and formation of mold would be substantially prevented by proper use of such a moisture sensor and indicator.
Additionally, dry pickup vacuum cleaners are designed to pickup only dry dirt and debris. A motor-fan assembly creates a suction for picking up dirt and debris which is filtered from the airflow by some type of filter assembly. The motor-assembly may be located either upstream of the filter assembly, commonly referred to as a direct air system, or downstream of the filter assembly, commonly referred to as an indirect air system. Exposing either of these two systems to a liquid would create a hazardous condition. The liquid would be drawn into the motor-fan assembly potentially shorting-out the motor. Shorting of the motor will at a minimum damage the motor components and could possibly result in arcing or fire.
Electronic moisture sensing devices are known in the prior art. For example, U.S. Pat. No. 4,374,379 discloses a moisture sensor for pipes that includes a pair of parallel, spaced electrical conductors that run along the lower side of a horizontally extending pipe. Should the pipe begin to leak, the water leaking from the pipe forms drops of water on the lower side of the pipe. The drops of water bridge the gap between the conductors, and thereby activate a circuit that turns on an audible or visible alarm.
An overflow control system for a clothes washing machine is disclosed in U.S. Pat. No. 4,418,712. One of the disclosed embodiments includes spaced electrodes or conductors located in an overflow pipe of a clothes washer. When the water in the overflow pipe bridges the gap between the electrodes, a circuit is activated that turns on an alarm and/or opens a circuit breaker to shut down the washer and prevent overflow of the washer.
U.S. Pat. No. 4,896,142 discloses a moisture detection system for a wet extraction type carpet cleaner that prevents overflow of the recovery tank. The disclosed arrangement includes two conductors mounted in a suction duct of a carpet extractor between the recovery tank and the suction fan. Should any moisture, foam or water overflow the recovery tank and enter the suction duct, the moisture will bridge the gap between the two conductors and thereby activate a circuit that automatically cuts off the power to the motor fan and prevents the moisture from entering the motor.
It is also well know in the prior art to provide dry pickup vacuum cleaners with acoustic or vibration sensors, for example, as disclosed in U.S. Pat. No. 5,608,944, or optical sensors, for example, as disclosed in U.S. Pat. Nos. 4,601,082 and 5,815,884, in order to detect dust flowing through a suction duct in the vacuum cleaner and indicate to an operator that the cleaner is picking up dust. An operator is thus prompted to continue cleaning a given area of carpeting until the sensor no longer detects any dust being picked up by the vacuum cleaners. At which point, the operator may move on to another area of carpeting, assured that the carpet has been fully cleaned before moving on.
The present invention provides a moisture sensing and indicating device for wet pickup vacuum cleaners, especially for carpet extractors, that indicates to an operator when the cleaner is picking up liquid or traveling over a wet area of carpeting.
It is an object of the present invention to provide a moisture sensor for a wet or dry pickup vacuum cleaner, and particularly for a wet carpet extractor or deep cleaner.
It is a further object of the present invention to provide an indicator for indicating to an operator of a wet or dry pickup vacuum cleaner when the cleaner is picking up moisture from the floor or traveling over a wet area of carpeting.
It is a further object of the present invention to provide an electronic sensor that senses the conductance of moisture in the suction duct of a wet or dry pick up vacuum cleaner and thereby determines when liquid is traveling through the duct.
It is a further object of the present invention to provide an optical sensor for determining when moisture and/or water is traveling through a suction duct in a wet or dry pickup vacuum cleaner.
It is a further object of the present invention to provide an acoustical sensor for determining when moisture or water is traveling through a suction duct on a wet or dry pick up vacuum cleaner.
It is a further object of the present invention to provide an electronic moisture sensor in a wet extraction type carpet cleaner that contacts the floor surface and measures the conductivity of the floor to determine when the floor is undesirably wet.
It is a further object of the present invention to provide an optical sensor for determining when moisture and/or water is present within or upon a floor to determine when the floor is undesirably wet.
It is a further object of the present invention to connect a moisture sensor in a wet or dry pickup vacuum cleaner to a circuit that activates an audible or visual alarm, preferably a lamp or buzzer, for indicating when the cleaner is picking up liquid from the floor traveling over a wet area of carpeting.
These and other objects that will become apparent to one of ordinary skill in the art upon reviewing the following description and the appended drawings are achieved by the present invention, which provides a moisture detection system in a wet extraction carpet cleaning appliance to indicate to an operator when the moisture concentration in carpet or other type of work surface has reached an acceptably low level.
In one illustrated embodiment of the present invention, a moisture detection system includes a moisture sensor which could be of the acoustic, thermal, optical, or conductive type. An electrical signal from the moisture sensor inputs to an appropriate alarm actuating circuit which optically or audibly relays the moisture content status of the carpet or work surface to an operator of the vacuum cleaning appliance.
The moisture detecting sensor according to the invention can either directly measure the moisture content of the carpet or floor surface, or indirectly electronically evaluate the carpet moisture content by monitoring the level of liquid being extracted through the extraction duct of the appliance. In a conductive sensor embodiment of the invention, a pair of spaced-apart conductors are positioned to contact the stream of extracted moisture. A sufficient level of moisture will act to bridge the gap between the conductors, and thereby activate an indicator circuit to indicate to the operator that a wet condition exists. An open circuit between the conductors causes the indicator circuit to communicate to the operator that a dry condition exists. The output signal from the conductors is routed through a buffer and a comparator which switches power between a first indicator lamp indicating a relatively high level of moisture in the floor surface and a second indicator lamp indicating a relatively low level of moisture.
The moisture indicator can be used to measure the moisture level of the floor surface and control the motor-fan assembly accordingly. The moisture indicator is electrically connected to the motor-fan assembly whereby as the cleaner passes over wetter areas of the floor surface, the moisture sensor will detect a greater amount of liquid and the control circuit will increase the power of the motor-fan assembly thus increasing the suction of the cleaner. When the cleaner passes over less wet areas of the floor surface, the moisture sensor will detect a lesser amount of liquid and the control circuit will decrease the power of the motor-fan assembly.
Additionally, the moisture indicator can be used on dry vacuum cleaners to disable power to the motor-fan assembly when moisture is detected on the floor surface or within the duct. When the moisture sensor detect the presence of liquid in the dry vacuum cleaner, the control circuit disconnects the power to the motor-fan assembly via a re-lay or other semiconductor device thus preventing the potentially hazardous condition of a liquid contacting the field and armature of the electrically charged motor.